The limit varies between 1-99 depending on your setting under "load balancing". If left blank, I assume the hardcoded limit is 99.

However, this does not mean that 99 users can actually use the EAP225 in a meaningful way. Depending on their usage pattern the link can be saturated with 20-30 users per frequency band due to the TCP/IP protocol, which in practice limits the number of users to ~40-60 for an EAP225 20-30 per frequency band x 2 bands). If they just send mail and don't use too much bandwidth, maybe the limit is raised to 80 or even 99 for both bands, but if they stream video, it will be much lower.