Open Google Chrome.
Navigate to chrome://settings/content/cookies.
In the Allow section, add [*.]oboard.online
Open Firefox.
Navigate to about:preferences#privacy.
Under Cookies and Site Data, click Manage Permissions...
Allow access for https://oboard.online
Open Safari.
At the top-left, click Safari and choose Preferences...
In the dialog that opens, go to the Privacy tab.
Under Cookies and website data, uncheck Block all cookies.
Unfortunately you cannot make an exclusion for a specific web resource.