Go to your Orchestrator services and download the enterprise version from that.
The LTS (Long term support) versions are 2018.4.x, 2019.4.x and now 2019.10.x is doing to be released. anything other than that (for example 2019.10.beta-ce etc.,) are not stable enterprise versions rather they are called FTS (fast track support) also, when you install it gives an option of 'get license from Orchestrator - do that and dont select community or stable version.
Do ll these as an admin as @Palaniyappan suggested and also end the UiPath robot service when you do that update/installation. And restart the system (also when you uninstall the older uipath the %appdata% still has residual files, those have to be deleted.) And pre-requisites are any .NET framework version greater than 4.7 (4.8 will also not hurt.)
Do these and get back if issue still persists.
PS : If you have enterprise license then you can also raise a ticket with UiPath product support for faster resolution. Also please see what licensing model you have (attended, unattended, development, non-prod etc), if it is attended yo can run any bots in un-attended mode. And if you acquire license from https://platform.uiapth.com then it will automatically a community free licensing model - so acquire license from your organization orchestrator (cloud/internal server)… Hope this helps