Select custom author page for custom role

I’ve made a custom author template model.php for a custom role model (Ultimate members Plugin) and I have the default author.php also. I want to assign model.php to model when someone goes to model a single page by keeping the admin.php the same for admin. I used this code.

This code is working as per my need by all the other pages of my website become a blank (white screen).

Can someone help me with this?