It seems that different users have different compatibility outcomes with the (original) YN-E3-RT.
Some people report issues with the 5DIV or 600EXII-RT when using the YN-E3-RT, and needed to upgrade to the YN-E3-RT II. I don't have the 5DIV or 600EXII-RT.
If you look at BH user comments you'll find various users citing compatibility issues.
However some other users have found the YN-E3-RT works well using the 600EXII-RT and the 5DIV.
If you have or use a EOS R, the general consensus is that you will have better operation with the YN-E3-RT II.
Here's a helpful site / page too.
Yongnuo YN-E3-RT II vs Yongnuo YN-E3-RT: Yongnuo have released their updated version but what's new and is it woth upgrading..
www.speedlitereview.com
It's up to you, but if I were you I would probably contact BH and ask if you can upgrade to a YN-E3-RT II (if you don't open the package).
Best wishes,
PJ