Maixduino board gives CRC error during inclusion in IDE

Arduino IDE 1.8.13: Tried to use following urls in preferences without success:
http://dl.sipeed.com/MAIX/Maixduino/package_Maixduino_k210_index.json
http://dl.sipeed.com/MAIX/Maixduino/package_Maixduino_k210_dl_cdn_index.json
https://raw.githubusercontent.com/JonRobo/Maixduino_Code/master/package_Maixduino_k210_dl_cdn_index.json https://dl.sipeed.com/MAIX/Maixduino/package_Maixduino_k210_index.json?id=arduino
Doesn't exist any more:
http://observat.io/MAIX/package_Maixduino_k210_index.json

When selecting and adding the Maix board a CRC error occures.
Has somebody tried it recently and succeeded?
Thanks in advance, Johan
PS Running the IDE under windows 10

You can try to install boards manually.

I have the same issue. I tried looking up on the internet on how to install the boards manually but couldn't find any information that explains to actually how to do this.

Any help would be greatly appreciated.

pierrewa:
You can try to install boards manually.
GitHub - sipeed/Maixduino: Arduino port on Maix board ( k210 )

Thank you for the helping hand. If I go to the github I can download "Maixduino-master.zip". I don't know where to put those files. According the install instructions the link http://dl.sipeed.com/MAIX/Maixduino/package_Maixduino_k210_index.json has to be included in the preferences of the IDE. So I am back from start.
In meantime I tried to copy the files of Maixduino-master.zip to the installation directory C:\Program Files (x86)\Arduino but without success.
(as per suggestion of https://forum.arduino.cc/index.php?topic=473761.0 )

I copied the downloaded here C:\Program Files (x86)\Arduino\hardware\Maixduino

Merci Pierre for this info.
Tried it and failed :frowning: .
Reinstalled version 1.8.13. I didn't try with other versions; perhaps this is the problem?
I had to delete the content of C:\Users\UserName\AppData\Local\Arduino15
But I keep getting this CRC error. I suspect that the json file contains invalid info because the CRC error didn't occur right after starting put fractions later.
Can you share the files you have copied in C:\Program Files (x86)\Arduino\hardware\Maixduino ?

johanbe:
Merci Pierre for this info.
Tried it and failed :frowning: .
Reinstalled version 1.8.13. I didn't try with other versions; perhaps this is the problem?
I had to delete the content of C:\Users\UserName\AppData\Local\Arduino15
But I keep getting this CRC error. I suspect that the json file contains invalid info because the CRC error didn't occur right after starting put fractions later.
Can you share the files you have copied in C:\Program Files (x86)\Arduino\hardware\Maixduino ?

Go to https://dl.sipeed.com/MAIX/Maixduino/ then select the folder named core.