Domain interface with gmail

Pardon me for a fairly long post, I desperately need some real help.
I have a domain, <redacted>.  It is registered with google workspace.  I have used it to send mass mailings to libraries to advertise books.  I have a separate google account for it and the email address is <redacted>.

For the first time in a year or two, I prepared to send a mass mailing via gmail from that address again.  Something, however, was wrong.  It seemed to be impossible to either send or receive an email from that account.  

I contacted google support.  The tech there suggested that I try using an icognito chrome window, and also that I cleear my cache. I did both, and presto, the incognito window worked--suddenly I could send and receive emails from that gmail account to my regular personal one.  (You can't send mass emails from gmail personal accounts, by the way.)  However, when I tried to load the spreadsheet that has all the mailing info, I got an error message that you couldn't load onto a google sheet in an incognito window!  So it was back to google.

And this time, when I began troubleshooting with a new tech, the incognito window didn't work anymore either!  In fact, the inbox no longer showed the messages that I had successfully sent to the <redacted> address earlier in the day!  That tech bounced me to a higher level of google workplace support.  Here is where things got really interesting.

The site, whois.com, informs us that my domain is registered by Squarespace Domains II LLC, a Canadian company.  It lists the name servers as ns1.securedserverspace.com and ns2.sercuredserverspace.com.  The tech then checked the data on my domain in the google admin toolbox at <redacted>.  Based on what he saw there, he advised me to send the following email to securedservicespace.com:<redacted>

Now, when you go to securedserverspace.com, you get a message suggesting that you must have gotten their by mistake.  The page does link an email address, however, webmaster@secureserverspace.com, and I sent that email there. That was about 6 PM EDT in the US last night.

Checking this morning, I noticed that that mysterious webpage had a link to CPanel at the bottom, and that CPanel seems to have some connection to secureserverspace.com.  So I followed that link, created an account, and found this forum.  I'm looking for answers to two  questions:

1.  How can I reach someone who can make the changes in the mx and txt values that google workspace is requesting?

2.  Does what the google tech said make sense?  It doesn't make sense to me, because, as I said, at one point yesterday afternoon, I could send and receive messages to/from the address <redacted> using an incognito window.  However, that only lasted for a couple of hours, and in any case, I need to do something to make normal windows work for it because that's the only way to send the mass email.

Thanks in advance!  I notice there are phone numbers for squarespace domains on the whois page, and I will try them during working hours.

David Kaiser