I downloaded the program and found some info that might help you install it.
I'm not a coder. I'm a Frankensteiner when it comes to code. But, over the years I have solved many program issues by doing some investigation of the code to see where things go. I'll post what I found and you can decide if you want to try it.
"DO THIS AT YOUR OWN RISK. I'M JUST MAKING A SUGGESTION. IT MAY CAUSE ISSUES."
1. Merge the folder 'Icons' into the same folder in the Max root. You can drag it in and when asked if you want to merge, say "yes" and it will just add the contents of the folder to what's already there. It won't erase anything.
2. Put the folder 'Unfold3dBridge' in the 'userscripts' folder in the Max root but most likely it should go in the Max 'ENU' folder that is here: 'C:\Users\%YourUserName%\AppData\Local\Autodesk\3dsMax\2016 - 64bit\ENU'
3. It looks like the file 'Titus_Scripts-UnFold3D_Bridge.mcr' goes in the 'usermacro' folder. It's in that same 'ENU' folder above. Just copy it out of the 'Macro' folder and paste it into 'usermacro'.
I'm not sure if all of this will work. It does appear as if the installer uses DotNet or something to write some XML files or something. I'm not sure as again, I'm not a coder. The developer's installer may also make some connections that you can't recreate by just placing files in folders.
You also can't fault the developer for not getting back to you in a short few hours. It may take a few days. Many times these small developers are 3d artists like you and I and they are busy. They'll need some time to get around to your email. That's where my suggestion to pay them $5 came from. 100's of people download the free stuff and then write for help for something that was FREE. I'm sure it's daunting for the developer. But, if someone gives you money, you are more likely to try to help them. Did you donate? If not, don't be surprised if you don't hear from them. I had a friend once who used to snag hacked software all the time and then bitch that it didn't work well. I told him to stop stealing software, pay for it, get support and get back to work. I'm not suggesting you snagged hacked software as this is FREE as you said. But, still, money talks and if you want help, $5 can go a long way.
Lastly, have you reset your 'ENU'? That path I gave you above is the ENU. Close Max and rename it to something like 'ORIGINAL_ENU' so Max can't find it. Then launch Max. Max will recreate that entire folder and its subfolders. Now drag the program in and see if it installs. It's likely it will. Then you'll just have to rebuild some of your Max customizations. There are ways to save that and you can search for help on that. But I'd try the renaming the ENU trick. If it doesn't help or work, just close Max, delete the new ENU that was created and remove the 'ORIGINAL_' from your original ENU and relaunch Max. You'll be right where you left off.
This is a good trick anytime Max is being funky.
Anyway, I hope this helps.
Rob Holmes

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3ds Max (2023-2025), V-Ray 6.2, Ryzen 9 3950-X Processor, DDR 4 128MB, Gigabyte Aorus X570 Master motherboard, Sabrent Rocket NVMe 4.0 M.2 drives, NVidia RTX 4090, Space Pilot Pro, Windows 11 Pro x64, Tri-Monitor, Cintiq 13HD, Windows 11 x64
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