Now the problem is that it takes almost one day to download the wallet while filesize is up to 98 MB. For some reasons, their servers don't let me to download it with normal internet speed and limit my download speed significantly.
I just downloaded it now and it took roughly 20 minutes to download with my personal internet connection. I do not think it is their server limiting your download speed and surely not intentionally. Could be an overload on available connections on the web server or some other reason.
Try clearing your cache and try again.
20 minutes is too much for 98 MB file unless you are using a cheap DSL internet with low speed and I personally use fiber optic and my speed is 100 Mbps. It should be downloaded in seconds instead of hours.
I finally managed to download it in one hour instead of a day. Thanks god, speed improved a little.
Maybe you experienced some temporary or local Github connectivity issues. And nobody except you can know what's going on in your local network.
20min for the download of ~100MB doesn't sound any fast either, but Eleutheria didn't mention any details of personal internet connection. Such a download time could happen when you only have something like 1MBit/s downstream.
Today I tried to download Sparrow Wallet again and the speed was improved but there were limits on download. There is definitely a problem on their side. I'll try to contact them and let them know about this issue.