ASM policy build

Please use this article - ASM operation guide - https://my.f5.com/manage/s/article/K85426947

i suggested rapid deployment policy because, it will not block anything by default. You can set policy reediness period and within time you will get traffic learning details from F5 GUI .The Rapid Deployment security policy provides security features that minimize the number of false positive alarms and reduce the complexity and length of the deployment period.

Please go through below link to understand more about rapid deployment - https://techdocs.f5.com/kb/en-us/products/big-ip_asm/manuals/product/asm-getting-started-12-1-0/7.html#:~:text=The%20Rapid%20Deployment%20security%20policy,Performs%20HTTP%20compliance%20checks 

Also , Please verify if your F5 have enough memory for ASM operations. Once you set ASM it will also consume CPU and memory.

BR
Aswin