Download app without WiFi

There's no workaround. The size limit on cellular downloads is fixed and not user adjustable. Get your Wi-Fi fixed or use iTunes on a computer to log in the App Store, download to the computer then plug in the phone and sync the phone. If you go the iTunes route, make sure to log in the App Store with the same AppleID the phone is registered to. App rights-to-use are permanently linked to the AppleID that acquires them, not the device.

If you use the phone as a hotspot for your computer. download the app onto your computer using iTunes then sync the phone to the computer via USB. Select the phone icon at the top of the iTunes window, choose Apps in the left column, find the new app, then use the Install button or drag the app to the desired phone screen. There is no size limit using iTunes.

https://support.apple.com/kb/PH19460

This is so asinine as I do not have a separate internet provider for my mac. I use my iphones hot spot. How do you suggest I get around the 100mb limit now?