it looks like you have just copied and pasted the URL which won't work.
If the photos are in an album on Google Photos do the following.
Open the album
Click the share icon on the top right of screen (looks like a sideways V)
Click on "get link"
Click on "copy" to copy the link
Paste the link in a post
https://goo.gl/photos/qG4TVGPMAMQ1Kf8Y6
If the photos are in an album on Google Photos do the following.
Open the album
Click the share icon on the top right of screen (looks like a sideways V)
Click on "get link"
Click on "copy" to copy the link
Paste the link in a post
https://goo.gl/photos/qG4TVGPMAMQ1Kf8Y6