Hi Katelyn, we just started using SAML at our organization. I have the same type of users as you do. What I did was first set up their organization account through my ArcGIS Online (AGOL) portal. I then either sent them their invitation email or, if I was standing behind their shoulder, emailed them a link to our AGOL portal. I had them open this link first to establish the account and then I emailed them a direct link to the Hub site that I wanted them to use. Going forward they only have to click on the link to the hub site and you can even create a desktop icon for them. So far so good but if I run across any issues from my users I'll post an update. We run an Azure AD system over here so Edge seems to be working the best when it comes to remembering user's credentials.
Hope this helps.