Hi @eytan.h and welcome back to the Auth0 Community!
Thank you for posting your question. During my research, I came across this post with a similar topic. As my colleague said, the terms MAU (Monthly Active Users) and EAU (External Active Users) are synonymous and are used interchangeably.
Regarding the limits you see in the subscription plans, they can be read as “currently the limit is 500 active users, with the possibility to increase the limit to 100.000 active users”
Please let me know if this is not clear, and I will help you as much as I can! 