Discourse has the try.discourse.org forum as a place to see user features. Maybe you could create a parallel forum as a place to see admin features? Something like tryadmin.discourse.org
I understand you have a 14 day free trial, but at this stage I am just exploring one or two features at a time, very informally.
How do you imagine that working? An admin has access to everything, but maybe you wouldn’t like it if other testers had access to your email address and your IP address. In order to try things out, you would also have to be allowed to change things. How do you ensure that this isn’t exploited, for example, that no one installs a theme component that spies on others?
It’s quite easy to set up a dev install in a GitHub codespace. I have used that for testing the admin experience before: Developing Discourse on GitHub Codespaces. Of course, any other dev-install works too.
Thanks, I will try Codespace
Also: trials are fast to spin up and do not require a credit card, no problem with you spinning up a few over the course of your evaluation 
@Bas, they appear to, now:
Perhaps, that’s a good reason to try the GH Codespaces option for those able to.
The reply you linked is from 2017. I do not remember there being a credit card requirement the last time I spun up a trial instance (a year or two ago)
Odd… the FAQ on Discourse pricing | Discourse - Civilized Discussion says:
Do I need a credit card to start a free trial?
No, you can try Discourse for free right away!
To combat spam attacks, we sometimes do require credit cards up front but we’ll never automatically charge you at the end of your trial.
But I clicked around and I could see no indication that a credit card was required. So perhaps not.
i spin up trials regularly for testing, and no they do not require a card
There is also the free plan now: You're invited to try the Discourse Free plan beta!
Ultimately, it depends a bit on what you want to test. The free plan is a bit more limited in terms of options, but it’s available indefinitely. The 14-day trials are time-limited, but they offer almost all features. With a development installation, you have all the options available, but you need to take care of it.
I just archived that old topic from when we had the requirement to avoid any additional confusion.
It’s possible that the system detects suspicious IPs and requires the card in that case but I’m not entirely sure. All I know is it’s never asked me, it might be different if your IP is from a datacenter
Blast from the past, wow. Yeah, that post is nearly 8 years old! As Bas and others have shared, we do not currently require a credit card to spin up a site. As Moin pointed out, we also have a free plan!
And Nate shared our current stance (as opposed to my ancient comment) from the sign up page itself. No credit cards required by default. We retain the ability to require one should we see an uptick in spam or other issues.