I was there in mid-May, about 3 weeks ago. I was also there last year, the day the new visa program started actually on April 1, 2025. My advice is to do visa on arrival - manual. This means grab the paper form in the airport, fill it out onsite (with the trusty pen you brought). This is different than the visa on arrival - electronic (meaning filled out ahead of time, but technically issued on arrival). It sounds confusing because it is, two types of VOA's, manual and electronic. As well as a visa which is actually granted ahead of time, not on arrival. Also, be aware not all nationalities are eligible for VOA's. Some nationalities have to apply well ahead of time before they ever get to Namibia, in the traditional sense of the process. That is one reason they have different systems. US citizens and many others are eligible for VOA.
I say all this because VOA-manual folks were directed to their own dedicated line, by far the shortest one. In fact, this way gets you through faster than anyone else in my experience, even though you are filling out the form and paying at the airport. I paid by credit card btw. You will get in, just be patient as has been said. Cheers