I have an Arduino plug and make kit and am experimenting with the modulino thermo template, but cannot get past the R4 Controller configuration as the safari web browser does not see the Arduino cloud agent, It seems this is a common issue and what is the fix?
unfortunately, I’ve encountered the same problem. My only solution has been to use Chrome.
I tried for hours, going through privacy, security & keychain settings on both MacOS and Safari, numerous re-installations of the Agent and still ‘does not see the installed plug in’ . I installed FireFox and it worked without any issues at all! What is going on? this shouldn’t be happening, any ideas anyone?
can you please check if the solution in this comment works for you?
https://forum.arduino.cc/t/web-editor-cant-connect-with-board-on-safari/1155322/2
I don’t see the option “Go To Arduino Create.” My first option is “Go To Arduino Cloud.” I also only see “Manage HTTPS Certificate” (presumably because I’ve already generated/installed the HTTPS cert?).
Sorry, I was referring specifically to “Manage HTTPS Certificate”.
If you click on it, you should see a dialog like this:
Can you please click on “Install the certificate for Safari” and refresh the page?
BTW, I also found this troubleshooting document:
https://support.arduino.cc/hc/en-us/articles/360018131160-If-your-board-is-not-detected-by-Arduino-Cloud-Editor
At point #6 you can find a step-by-step guide about this.
Let me know if that works for you 
I’ve gone through everything to do with privacy, security and it will not work, it says looking for missing plug in, I gave up and used Firefox and it worked with no issues, but I shouldn’t have to be looking for work arounds.
I’ve also gone through all the steps as well (including #6). Never gotten it to work with Safari, I just have to switch to Chrome.