When sending out emails, it depends a lot on whom you address, how you address them, and what the topic is.
If you wrote "I need your help" and sent the emails to companies, than 0,5% return rate would be a typical rate.
If you addresses personal friends, asked them about some viral Instagram posts, then I would expect 50% or more. It's really ambitious to exceed 60%.
Given non-professional email addresses, a polite email and an interesting topic, I would expect somewhat 5% to 25% return rate.
have "only" received 554 clicks
A "click" is not very concise. That could be an actual click, but also the social media platform loading a preview of the page. However, having a lot of clicks and no dataset could also mean that your welcome page was ... suboptimal. Take a look at the manual Tips for the Survey Design
Also try and send the email to a few friends (Gmail ans GMX addresses, for example) and ask them if it has arrived. This sould be a good test to see, if spam filters were over-active regarding your email.