My DKIM signature is not valid - emails going to SPAM!

Hi, I am having problem since all the emails I send go to SPAM. Apparently my DKIM signature is not valid and I don't know how to fix this.

I have domain and hosting purchased in Hostgator with cPanel and I purchased professional email accounts with Hostinger (Titan). I can provide access to everything.

Please help! It's kind of urgent.