I'm not aware of any issues. If you have problems in general on itch then you have to contact their support. If it's only with Renryuu, than maybe try this alternative download link for the time being: https://mega.nz/file/KgoQ2I5C#obSRVrQ1hDlE0_RhoAukEeBNHH8S8nB5e8362j8UX0E