I got the error too!
We will change the error message.
Your image must be under 100ko.
I suggest that you use an online tool like: https://bulkresizephotos.com/ to resize your picture.
Try with a max width at 300 pixels. It should make it!
If possible, use a square format for your profile pic. It looks better on the site
Sorry for the inconvenience. In the future, we will allow people to upload any-size images and we will automatically resize it during the upload. Just give us a few more weeks...