How to test APM access policy locally?

Just create a web virtual server. F5 is Linux so making an apache web server virtual machine will help you with F5. You can use the APM local user database but I will also say that if you want to learn find Appliance image of Radius or TACACS and import it in the Virtual Box or even a windows server as they have 180 days trial licenses and make an AD. Also better use Hyper-V on windows 10 as it is free.

https://techdocs.f5.com/kb/en-us/products/big-ip_apm/manuals/product/apm-authentication-single-sign-on-11-6-0/13.html