Chapter 6 of the NEC provides requirements for special equipment. The first type of such equipment it covers is electric signs and lighting, in Article 600.
Article 600 applies to the conductors, equipment, and field wiring for electric signs or outdoor lighting regardless of the voltage [600.1]. It gives some examples of the types of lighting covered, but if something isn’t mentioned it’s still covered.
You must use listed equipment and install it per the listing requirements [600.3]. The manufacturer knows the listing requirements and includes installation instructions so that you can meet this requirement.
Don’t make assumptions based on expedience or convenience. For example, the instructions show an enclosure in a specific orientation. There’s an opening for your raceway fitting near the bottom. But it would be easier for you to install this upside down. Can you do it?
Maybe the opening is near the bottom to permit drainage of water that may enter the enclosure. The device is listed for installation in this position, which is why the instructions don’t mention anything about flipping it over. So the answer is no.
You could contact the manufacturer and ask about this. Then, armed with an e-mail or letter that gives permission, you then get permission from the Authority Having Jurisdiction (AHJ) to install it upside down. Generally, this much effort isn’t worth it. But if you’re going to deviate from the installation instructions, that’s the kind of effort you’re required to make.