(google translate)
You have completed the simplest installation attempt, but sometimes such a situation occurs that makes you unable to continue.
When you do not see the description file in "VPN and Device Management", you need to use Sideloadly to install it manually and consume one of the three quotas for third-party applications provided by the free Apple account.
The steps are very simple, and basically the teaching text allows you to complete all the steps, although I still struggled for a long time.
Here I will give you some tips and highlights:
1. You need a computer and make sure that the computer’s iTunes is the official version, not the Microsoft version.
2. Use a web browser to go to the iosgods app to download the IPA file.
3. After downloading Sideloadly, open iTune and Sideloadly. You need to enter your apple account in Sideloadly, then insert the loaded IPA file, and then Start.
4. After completion, the application will appear on your phone. Next, go to "VPN and Device Management" as usual, but trust your Apple account.
5. Complete.
*My friend upstairs seems not to have fully understood your description. XD
Hope this helps you.