I’m getting error when calling https://api.company-information.service.gov.uk/company/05822443
The company exists and the URL looks OK. When you actually request that endpoint do you have a trailing “/” at the end e.g. … /company/05822443/ - that apparently causes problems.
But what error are you getting (what http response code)? What system / software / package / language / library are you using to call Companies House? Did you register a live application or a test one (hint - use a live one…) Are you calling from a server environment (e.g. fixed IP) and did you register it (if you’re calling from a local host did you use the workaround for that - search this forum for details), and if not did you register the domain you’re calling from?
Have you searched this forum to see if the error you received might be covered (hint - it almost certain is - and indeed there’s probably a post covering your particular software / language / environment also)?