Can't exclude files so backup times out

I’m trying to backup my WP site and exclude certain folders because if I don’t, I’ll get a timeout message.

However, when I click on “excludes”, a window opens and it just hangs there with a whirring icon so I can’t do anything.

Unless I can get this to work, I’m going to have to use another plugin which sucks because I’ve been using this one for quite some time without any problems. ??

https://www.ads-software.com/plugins/backupwordpress/