Yes, I have checked from my side it's working, but the assign limitation for Number of blog per level not working that means, I was tried with Premium Level that has 5 limits for creating the subsite, but after creating 5 sites by that users, he again create 6th site, that is wrong it would get message for you to have only 5 limits for creating Subsite.
Please, check this from your side.
I have updated "ps-sites-per-level.php" with your shared GitHub link, but it's not showing screen as you shared for "Create New Site".
after clicking Add new Site from Current Active Plan it's showing the following details, Screenshot attached.
Yes, I also get "Sign for another site", but after when clicking on "Sign for another site"it's asking another site name, its good but after clicking reserve the site its again redirect for payment for those Users who already taken the plan that allows creating a number of blog per level, this is not good.
I need to fix this issues, that means after taking any plan users will create the Number of Sites as per taken plan.