Install fails

First clear cache (/admin/config/development/performance) and the run /update.php.

If it doesn't work, uninstall the theme first using info from here: https://www.drupal.org/docs/extending-drupal/uninstalling-modules →

i tried, didn't work (composer remove drupal/zeropoint, flush all caches, composer require 'drupal/zeropoint:^1.7' etc).

I found solution and I'll write that down, maybe it's good for others to know:
I searched the entire site database (w phmyadmin) for 'zeropoint' (after removing theme), and found a lot of matches (mostly migrated blocks w zeropoint string in name, 40 fields in migrate_map_d7_blocks etc).
The installation was successful after I manually deleted the field 'zeropoint.setting' from the config table.