Our site is secure, so any non-secure URL will not appear on your page. 
But, there is a trick:
To know if the URL is secure, the address will have an "s" in it: https://
 A non-secure address will not: http://
Try adding and "s" to the link after you paste it 

If you are using a URL from any third party sites, like Soundcloud.com, youtube.com, vimeo.com, scribd.com, slideshare.net or polleverywhere.com, the full URL may not work in Velop.

Find how to manipulate the URL 

slideshare- powerpoints

Scribd- documents 

Soundcloud- audio

For most other sites the URL or embed URL they provide will work.
If you run into a link that is not working, email Ashley for support at ashley@needsmet.org