why does my phone have select mock location app and not allow mock location

[AC Question]

i am currently trying something out with my phone that i have seen on an app that i have to allow mock location , but when i go into my phone and do the steps its only coming up select mock location , is there a way to be able to allow mock location on my Sony Xperia M4 Aqua ?

i have been trying for days and was wondering if you might be able to help

thanks Rebecca