Download the OpenCOLLADA plug in for 3ds Max from https://github.com/RemiArnaud/OpenCOLLADA/releases
Extract the zip file and copy the plugin (ColladaMaxNew.dle) in the “plugins” directory of the 3dsMax installation folder .If you compile the plugin yourself, you’ll find it inside OpenCOLLADA\COLLADAMax\bin\win\[Win32 or X64]\.. folder.
For example, if you have Max 2021 installed at “C:\Program Files\Autodesk\3ds Max 2021\3dsmax.exe” then copy ColladaMaxNew.dle in the “C:\Program Files\Autodesk\3ds Max 2021\plugins\” folder. Note this path is for a 64bit version. 32 bits applications are in “Program Files (x86)” folder.
Open 3ds Max or restart if it was open when you installed.
Open up your scene, choose File | Export
Select OpenCOLLADA (*.dae) from the drop down box, give the file a name, and press Save button.
This will open the OpenCOLLADA Export dialog.