Issue

Embedding PowerApps on SharePoint On-Premises will not work on HTTP protocol in Google Chrome. 

An infinite loading circle will be displayed instead of the application.

Solution

Either upgrade the hosting site to HTTPS or try to use other browsers (Mozilla, Edge, etc)

Related Articles 

• Adding Your First PowerApps Application to SharePoint
• Embed PowerApps on SharePoint On-Premises and SharePoint Online (cross-tenant)