How do I install Altmetric on my Macbook pro? I am using Safari. Your help would be much appreciated.
To install the bookmarklet you will need to go this page. https://www.altmetric.com/products/free-tools/bookmarklet/
Then click on the "Altmetric It" bookmarklet button and drag it to the bookmarks bar.
This video will show you an example of someone adding the bookmarklet to their browser page.
Yes, I have tried that but get the following message: see the attachment:
What is the Develop Menu and where can I find it??
The issue you are seeing is within the MacOS interface and not with the Bookmarklet.
Below are the instructions on the mac help page.
Unfortunately I won't be able to help beyond providing these links. If the issue persists I suggest you contact Apple support.