Nite ize makes a variety of products, for example https://www.amazon.com/dp/B00KSKY0KS/ref=cm_sw_r_cp_apa_glt_fabc_TCRHDJ7MWV0704H72FHG
If webbing is ok instead of rope then there are many buckets, cam, or ratchets. https://www.amazon.com/dp/B0774KKHWF/ref=cm_sw_r_cp_apa_glt_fabc_0C5TMQ242E8N9GYQ4BN5
There are tons of rigging, sailing, and climbing products but you'd need to describe your use case in more detail.
There are also knots like a clove hitch that can be used with a carabineer, tensioned, and adjusted very easily.
With no structure mods, you’ll probably want something that slides around the door, like this: https://youtu.be/2szMTyvPLvU
Or if you or someone you know are handy, you could probably build something like https://nightlock.com/door-security-devices/door-barricade/nightlock-lockdown-2/ except that has a “U” attachment to go around the bottom of the door while not actually mounting to it — just with enough friction stay put when not in use. Basically an easier to manage one-sided version of the above.
Or tie a rope around the doorknob, and attach to something heavy. Add a few small carabiners and a paracord quick tensioner, and that could be easy to work with…and not be noticeable at all to those outside like those above. One of these https://www.amazon.com/dp/B00KSKY0KS/ would make it quick and easy to setup and take down. Just leave a small loop always tied to the handle, clip to that, and tighten.
(Side note — what are the actual terms in the lease as written on this? That could be meaningful.)
How about this?
Cam Jam XT Aluminum Tie Down Rope Tightener with Carabiner Clip https://www.amazon.com/dp/B00KSKY0KS/ref=cm_sw_r_cp_api_i_CMBHC3BNKBGNYRQWNKR7
I purchased something like this to do a similar thing. Just add weights.
Nite Ize CamJam XT Aluminum Tie Down Cam Mechanism With Carabiner Clip
How about this: Nite Ize CamJam XT Aluminum Tie Down Cam Mechanism With Carabiner Clip https://www.amazon.com/dp/B00KSKY0KS/ref=cm_sw_r_cp_api_glt_fabc_TBX0YDFRMF4NG995AVJG?_encoding=UTF8&psc=1
I love these for that same purpose, also by Nite Ize. These work great with paracord and it's easy to keep the attachment out of reach. :)
https://www.amazon.com/Nite-Ize-Tightener-Versatile-Mechanism/dp/B00KSKY0KS/
This is how I did mine starting from weight on the chair, use my gymnastic rings strap to secure around the handle. 2 of these tie down things to clip into the strap. I use paracord to go up, through the 2 pulled and back down to the other tie down. This let's me use a clip at the turn around point so it can slip and even out the slack (I hate having them be uneven, ensures both the tie downs to evenly distribute the load). I can clip whatever onto the carabiner. The handles I have on in the picture I use for straight arm lat pull downs (laying on my back on the floor) to supplement front lever, or you can use just one handle to easily scale one arm pull-up. Figure out a way to fasten it to a climbing harness or dip belt to create a dream machine for front levers, planche, iron cross, etc.