The easiest way for you to do this is to download the apps you want on a computer, put them on a USB stick or SD card and then open them in the File Manager on the PPM to install them. You can download the apps for instance on APKMirror or APKPure.
With some apps (so called bundles), you also need to install a separate installer program first. This can also be done in the same way (download, put on stick, install). Please see further information about these installer programs on the APK web site of your choice.
If itās only downloading of apps they are restricting then why not just hotspot your phone to download the apps? apps donāt take too much data, unless they are restricting data when youāre using the apps too?,
Or download the apps on your pc and then side load the apps
Iām also with BT and having no problem downloading apps from Aptoide.
However, I couldnāt directly download the apkmirror installer (but I havenāt investigated why it didnāt work).