For all our products, we do offer a free, 14-day, fully-featured trial. To access this free trial, simply start using the product! (If unsure how to get started, check under the "Getting Started" section here in the Support Portal of the product you want to use, there should be instructions how to install/setup the product.)
Once the trial expires, for some products it will go into a 'free' mode where you can continue to use it with some limitations.
Google Sheets: No scheduled refresh, 100 max rows per query, 100 queries per day, Google Analytics only available connector to use
Data Studio: Single assigned user, one ad account per ad network, max date range of last 10 days, only these connectors available to use - Facebook Ads, Twitter Ads, Microsoft Advertising, LinkedIn Ads, MailChimp, Google Analytics, Google Ads, Google Search Console, and Yahoo Gemini
BigQuery: No free mode
Excel: No free mode
Uploader: No free mode
Legacy products: No free mode