Can't make it work on D9.3

Hi,
Thank you so much for this needed module that we are using on D7 successfully for years.

Migrating to D9.3 and tried both 2.x-dev and 1.x-dev and just can't make it work. In browser it gets redirected to the proper URL, but user is not logged on.

php 01/05/2023 - 23:03 RuntimeException: Failed to start the session because… Test User
php 01/05/2023 - 23:03 Warning: htmlspecialchars() expects parameter 1 to be… Test User
urllogin 01/05/2023 - 23:03 Logging in as (15979). Redirected to: visual-aids Test User
php 01/05/2023 - 23:03 Warning: htmlspecialchars() expects parameter 1 to be… Test User
php 01/05/2023 - 23:03 Warning: htmlspecialchars() expects parameter 1 to be… Test User
php 01/05/2023 - 23:03 Warning: htmlspecialchars() expects parameter 1 to be… Test User
urllogin 01/05/2023 - 23:03 Logging in as (15979). Redirected to: visual-aids Test User
php 01/05/2023 - 23:03 Warning: htmlspecialchars() expects parameter 1 to be… Test User
php 01/05/2023 - 23:03 Warning: htmlspecialchars() expects parameter 1 to be… Test User
user 01/05/2023 - 23:03 Session opened for Test User. Test User
urllogin 01/05/2023 - 23:03 User Test User (15979) successfully validated Anonymous

And below the detailed error message:
User Test User
Location http://d9.healthplexus.net/l/VFaSTtBpjtKq/visual-aids
Referrer
Message RuntimeException: Failed to start the session because headers have already been sent by "D:\WebSites\d9.healthplexus.net\vendor\symfony\http-foundation\Response.php" at line 1239. in Symfony\Component\HttpFoundation\Session\Storage\NativeSessionStorage->start() (line 152 of D:\WebSites\d9.healthplexus.net\vendor\symfony\http-foundation\Session\Storage\NativeSessionStorage.php)
#0 D:\WebSites\d9.healthplexus.net\web\core\lib\Drupal\Core\Session\SessionManager.php(162): Symfony\Component\HttpFoundation\Session\Storage\NativeSessionStorage->start()
#1 D:\WebSites\d9.healthplexus.net\web\core\lib\Drupal\Core\Session\SessionManager.php(193): Drupal\Core\Session\SessionManager->startNow()
#2 D:\WebSites\d9.healthplexus.net\vendor\symfony\http-foundation\Session\Session.php(191): Drupal\Core\Session\SessionManager->save()
#3 D:\WebSites\d9.healthplexus.net\web\core\lib\Drupal\Core\StackMiddleware\Session.php(61): Symfony\Component\HttpFoundation\Session\Session->save()
#4 D:\WebSites\d9.healthplexus.net\web\core\lib\Drupal\Core\StackMiddleware\KernelPreHandle.php(48): Drupal\Core\StackMiddleware\Session->handle()
#5 D:\WebSites\d9.healthplexus.net\web\core\modules\page_cache\src\StackMiddleware\PageCache.php(191): Drupal\Core\StackMiddleware\KernelPreHandle->handle()
#6 D:\WebSites\d9.healthplexus.net\web\core\modules\page_cache\src\StackMiddleware\PageCache.php(128): Drupal\page_cache\StackMiddleware\PageCache->fetch()
#7 D:\WebSites\d9.healthplexus.net\web\core\modules\page_cache\src\StackMiddleware\PageCache.php(82): Drupal\page_cache\StackMiddleware\PageCache->lookup()
#8 D:\WebSites\d9.healthplexus.net\web\core\modules\ban\src\BanMiddleware.php(50): Drupal\page_cache\StackMiddleware\PageCache->handle()
#9 D:\WebSites\d9.healthplexus.net\web\core\lib\Drupal\Core\StackMiddleware\ReverseProxyMiddleware.php(48): Drupal\ban\BanMiddleware->handle()
#10 D:\WebSites\d9.healthplexus.net\web\core\lib\Drupal\Core\StackMiddleware\NegotiationMiddleware.php(51): Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle()
#11 D:\WebSites\d9.healthplexus.net\vendor\stack\builder\src\Stack\StackedHttpKernel.php(23): Drupal\Core\StackMiddleware\NegotiationMiddleware->handle()
#12 D:\WebSites\d9.healthplexus.net\web\core\lib\Drupal\Core\DrupalKernel.php(708): Stack\StackedHttpKernel->handle()
#13 D:\WebSites\d9.healthplexus.net\web\index.php(19): Drupal\Core\DrupalKernel->handle()
#14 {main}

Could someone please help with this error or point in the right direction?
Thank you!