WSS app launches Assetto Corsa, but it closes itself with ‘Checksum error’
Some mods might have been overwritten after installation, please try resetting installed mods in WSS app: click on menu icon, Game content > Reset game content and refresh page.
Server may also kick with red screen if Real penalty is enabled and you don't have Real penalty client app active - in this case please see 'Install manually' section here: Real penalty