When configuring SAML you can use the SAML group pattern to match SAML Groups to Zabbix Groups and Zabbix Roles. Let's say you have 2 Zabbix Roles (admin + user) and 4 Zabbix Groups (allowing access to different host groups) then you have to create 2 x 4 = 8 different SAML Groups + group mappings.

It would be more easy to use regex and regex groups in the SAML group pattern field. Thus you could handle the 8 group mappings in just one rule, e.g.:

SAML group pattern: zabbix-grp_(.)-role_(.)
User groups: Group-\1
User role: Role-\2

\1 and \2 should be references to the regex group in SAML group pattern.