Every online service seems to have their own set protocol to upload data with. The hardware/software that you use is what determines where it can upload to. Your station was only seemingly designed to upload to WU and to Ambientweather.net. But there is something you can do.
There is an individual very nice person not affiliated with Ambient that started a free online service. His name is Dan. He runs AmbientCWOP.com and his service can be configured to pick up your station data from Ambientweather.net and send it to your own CWOP station ID. Then you are done and your data will show up on Windy. This is because Windy picks up and shows stations that upload to CWOP. What you need to do is sign up for a CWOP station ID. Then you configure your free AmbientCWOP.com account and configure it to pick up your Ambientweahter.net data and send it to your CWOP ID.
(you don't have to configure the CWOP to MADIS link nor the MADIS to Windy link as these happen automatically).
There is something else you can do if you want to cut all the middle stuff out. After all you'd be relying on all those links and things often go down. Therefore here is another solution how you can upload directly to Windy.com...You buy an Ecowitt GW1000 gateway device. This is compatible with your outdoor weather sensor array from Ambient. Then you can interface the GW1000 with any of the following software and any of these software are capable of uploading directly to Windy.com. These are; Cumulus MX, Meteobridge, Weather-Display, and WeeWX. The Meteobridge is its own little devide that you can buy from Ambient. The other software you can download and run on any spare computer or even a Raspberry Pi. Remember any of these 4 software require the Ecowitt GW1000 that you must get from Amazon US or directly from Ecowitt and specify 915 MHz. If you buy the Ecowitt GW1000 from Amazon US then you don't need to specify the 915 MHz version because that is the only one that is sold for the US. You'll be able to send your data to many more places than just Windy if you invest in these expansion to your weather station. This investment in will likely work for a new weather station if you decided to replace it with a newer Ambient station or with a complete new Ecowitt station. The Meteobridge and software will also work with many other brands if you decided to change to a Davis station. I'm mentioning this because it is a worthy investment.