iPhone users will help you if you are prompted by "Untrusted Enterprise Developer" when installing 55.comAPP.
————Please follow the steps below————
1.Go to Settings → General
2.Pull the General to the bottom and select "Profile" or "Device Management".
3.In the "Profile" or "Device Management", you can see the description file.
4.Click on this description file to see the details.Then we click to trust this description file.
5.The iPhone pops up a dialog window asking if you trust the file and select "Trust".
6.After trust, the description file will look like the following image, and once again, return to the desktop and click on the "55.com" application to open it normally.