Basic authentication using username and password won’t work on Jira Cloud. You need to generate special token to authenticate in third party sites / applications.

Video showing generation of API token and first login:

Step by step instruction:

1. Create an API token

Create an API token from your Atlassian account:

1. Log in to https://id.atlassian.com/manage/api-tokens.

2. Click Create API token.

3. From the dialog that appears, enter a memorable and concise Label for your token and click Create.

4. Click Copy to clipboard, then paste the token to your script, or elsewhere to save:

Note:

• For security reasons it isn't possible to view the token after closing the creation dialog; if necessary, create a new token.

• You should store the token securely, just as for any password.

Source: https://confluence.atlassian.com/cloud/api-tokens-938839638.html

2. Log in through Excel 365 Connector for Jira

Use access token generated.

3. When you successfully log in

You will see some options allowing you to start working with Jira

note

Make sure, app is installed on your Jira and have active license: Installation - Jira Add-on

At this article you can find answer for following questions:

What can I do when I get error “API Token is invalid” ?