gmail rejects email from my domains

About 50% of my emails from my email accounts created to my domain get rejected as spam by gmail (and gmail only). This is the error I get:

 host gmail-smtp-in.l.google.com [142.251.163.27]
   SMTP error from remote mail server after pipelined end of data:
   550-5.7.26 This message does not pass authentication checks (SPF and DKIM both
   550-5.7.26 do not pass). SPF check for [pointlomaclinic.com] does not pass with
   550-5.7.26 ip: [66.96.184.1].To best protect our users from spam, the message
   550-5.7.26 has been blocked. Please visit
   550-5.7.26  https://support.google.com/mail/answer/81126#authentication for more
   550 5.7.26 information. t132-20020a37aa8a000000b006fcc017214esi5191652qke.217 - gsmtp
Reporting-MTA: dns; bosmailout01.eigbox.net

When I visit the gmail link, I am given a very complicated set of instructions, which flounders at the initial step of wanting me to sign in to an "administrator account" on one of my gmail accounts (and I have a few). Im not sure how anything I can do on MY gmail account will help me send an email from my domain to someone else's gmail account. 

I'm sending the emails from Apple Mail. 

Please advise.

Thanks