The BSDF files that Okalux was kind enough to share with use can be downloaded here:
If you are planning on actually using Okalux on a project, I recommend you contact a sales rep directly since I don’t know if they are still selling those specific products.
If you are just looking for a generic light diffusing material, it might be safer to use another file. The reason why I recommended you ask your question on this forum is because there are a number of others here who know good sources for BSDF materials. In particular, I know @sarith knows of some good sources to obtain some generic types of BSDF materials. He’s also the best source for running annual daylight simulations with BSDF materials, which is only possible in Honeybee[+] and not legacy Honeybee.
-Chris